WO2014207815A1

WO2014207815A1 - Heat dissipation substrate and manufacturing method for same

Info

Publication number: WO2014207815A1
Application number: PCT/JP2013/067327
Authority: WO
Inventors: 典明種子; 高木　剛; 知広武鑓; 秀吉瀧井
Original assignee: 株式会社メイコー
Priority date: 2013-06-25
Filing date: 2013-06-25
Publication date: 2014-12-31
Also published as: JPWO2014207815A1; JP6169694B2

Abstract

A heat dissipation substrate is provided with a substrate main body comprising an insulating layer and a conducting layer, a through-hole (5) extending through the substrate main body, a thermally conductive body (7) comprising thermally conductive material and housed within the through-hole (5), a gap portion (8) which exists as an interval between the through-hole (5) and the thermally conductive body (7), and a fixed plated portion formed by way of a plating process in the gap portion (8) in order to secure the thermally conductive body (7) to the through-hole (5). For the gap portion (8), an interval between the outer peripheral surface of the thermally conductive body (7) and the inner wall surface of the through-hole (5) facing the same is formed as non-uniform and has minimum portions (24) which are of a minimum interval and maximum portions (23) which are of a maximum interval.

Description

Heat dissipation board and manufacturing method thereof

The present invention relates to a heat dissipation board used for, for example, an electric control device for a vehicle, a household device, an LED component, or an industrial device, and a manufacturing method thereof.

半導体 Semiconductor elements in electric circuits tend to generate more heat due to higher density and higher current. In particular, a semiconductor using Si causes malfunction and failure when the ambient temperature is 100 ° C. or higher. Examples of such heat-generating components such as semiconductor elements include switching elements such as IGBT (Insulated Gate Bipolar Transistor) and IPM (Intelligent Power Module).

¡To effectively cool the heat-generating components, a heat dissipation board is used in which a heat dissipation path is formed on the opposite side of the board from the component mounting surface. Specifically, the heat generated from the heat generating component is conducted to the back side of the substrate (on the side opposite to the component mounting surface (mounting surface)), and cooled on the back side using a heat sink or the like.

As a method for forming the heat dissipation path, for example, a thermal conductor made of a metal having high thermal conductivity (Cu, Al, etc.) is disposed in a through hole formed in the substrate, and the thermal conductor is fixed in the through hole. There is a way to do it. The metal is fixed to the through-hole by adhesion by press-fitting or plastic deformation, joining by an adhesive or solder, and the like (see, for example, Patent Document 1). The heat generation component is radiated by connecting the heat conductor to the heat generation component and radiating heat generated from the component to the outside through the heat conductor (for example, columnar copper).

JP 2010-263003 A

However, if the thermal conductor is fixed in the through hole by press-fitting, stress is generated along with the press-fitting, so that a crack occurs in the prepreg (composite material made of glass cloth and epoxy resin) forming the insulating layer of the substrate. There is a fear.

In addition, if the heat conductor is fixed in the through hole by plastic deformation, the diameter of the heat conductor is made smaller than the diameter of the through hole when inserted into the through hole, and is fixed by plastic deformation by pressurization after insertion. Will do. At this time, if the center positions of the heat conductor and the through hole are shifted, a gap may be generated between the heat conductor after plastic deformation and the through hole. Also, if the pressure to cause plastic deformation of the heat conductor is large, the amount of plastic deformation spreading in the radial direction of the heat conductor is not always constant, and a gap is also generated between the heat conductor and the through hole. There is a risk. The presence of such a gap causes a shortage of solder for mounting due to penetration of the solder used for mounting the heat-generating component, and causes problems such as a decrease in yield and a decrease in connection reliability. Further, since a strong stress acts on the substrate in a portion where no gap is generated, there is a possibility that the insulating layer is broken.

The present invention takes the above-described conventional technology into consideration, fixes a heat conductor in a through-hole using plating, and a heat dissipation board that does not cause a gap between the heat conductor and the through-hole, and An object is to provide a manufacturing method.

In order to achieve the object, in the present invention, an insulating layer made of an insulating resin material, a conductive layer made of a conductive material, a substrate body made of the insulating layer and the conductive layer, and a through-hole penetrating the substrate body, A heat conductor made of a heat transfer material accommodated in the through hole, a gap portion existing as an interval between the through hole and the heat conductor, and fixing the heat conductor to the through hole. Therefore, the gap portion is provided with a fixed plating portion formed by plating, and the gap portion has a non-constant interval between the outer peripheral surface of the heat conductor and the inner wall surface of the through-hole facing the heat conductor. And providing a heat dissipation board having a minimum portion having a minimum interval and a maximum portion having a maximum interval.

Preferably, the internal space of the through hole and the heat conductor are substantially cylindrical, and the maximum portion is a substantially semi-cylinder that bulges outward from the inner wall surface of the through hole along the penetration direction of the through hole. It is formed by a protruding portion having a shape.

Further, in the present invention, a substrate body forming step for forming a substrate body in which a conductive layer made of a conductive material is formed on an insulating layer made of an insulating resin material, and an internal space penetrating the substrate body is a substantially cylindrical through hole A through-hole forming step of forming a metal, an insertion step of inserting and arranging a substantially cylindrical heat conductor made of metal in the through-hole, and a plating process in a state where the heat conductor is held in the through-hole A fixed plating step of forming a fixed plating portion made of plating in a gap portion existing as a gap between the through hole and the thermal conductor, and in the through hole forming step, Provided is a method for manufacturing a heat dissipation board, wherein a plurality of substantially semi-cylindrical protrusions bulging outward from a wall surface along the penetration direction of the through hole are provided.

Preferably, in the fixed plating step, a holder made of a porous body through which a plating solution can pass is disposed at both ends of the through hole.

According to the present invention, since the interval between the outer peripheral surface of the heat conductor and the inner wall surface of the through hole facing the heat conductor is formed as non-constant, the gap portion is the shortest portion and the maximum interval that are the shortest intervals. Therefore, the plating metal for forming the fixed plating portion can be sufficiently filled through the maximum portion. That is, since the plating solution flows into the maximum portion during the plating process, the plating metal can be surely deposited around the heat conductor. Furthermore, by providing the maximum part, it is possible to increase the contact area between the heat conductor and the through hole through the fixed plating part, and it is possible to fix more firmly. Can be fixed inside.

Further, the internal space of the through hole and the heat conductor are formed in a substantially cylindrical shape, and the maximum portion is formed by a substantially semi-cylindrical protruding portion that bulges outward from the inner wall surface of the through hole along the penetration direction of the through hole. Thus, the protruding portion can be easily formed, so that the maximum portion can be easily formed.

It is a flowchart of the manufacturing method of the thermal radiation board which concerns on this invention. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order, and is the heat sink which concerns on this invention. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order. It is the schematic explaining the manufacturing method of the heat sink which concerns on this invention in order.

A method for manufacturing a heat dissipation board according to the present invention will be described with reference to the flowchart of FIG.

In the substrate body forming step (step S1), the substrate body 1 as shown in FIG. 2 is manufactured. In the example of FIG. 2, the substrate main body 1 is a so-called four-layer substrate, and four conductive layers 2 made of a conductive material serving as a conductor pattern are formed via an insulating layer 3. More specifically, a so-called double-sided plate 4b in which the conductive layer 2 is formed on both sides of the insulating layer 3 is sandwiched by using two so-called single-sided plates 4a in which the conductive layer 2 is formed only on one side of the insulating layer 3, and this is laminated. By doing so, a four-layer multilayer board is obtained. Here, the insulating layer 3 is made of an insulating resin material, for example, a prepreg. The conductive layer 2 is made of a conductive material, for example, copper. As long as the insulating layer 3 and the conductive layer 2 are laminated on the substrate body 1, the number of laminated layers can be selected as appropriate.

Next, a through hole forming step (step S2) is performed. In this step, as shown in FIG. 3, a through hole 5 penetrating the substrate body 1 is formed. The through-hole 5 is formed using, for example, a drill or a laser. The hole shape after drilling, that is, the internal space of the through hole 5 is substantially cylindrical. The detailed through-hole forming step will be described in the fixed plating step (step S5) described later.

Next, a plating process (step S3) is performed. In this step, a plating process is performed on the substrate body 1 in which the through holes 5 are formed. Since this plating process is performed on the entire surface of the substrate body 1, the plating film 6 deposited by the plating process is formed on both surfaces of the substrate body 1 and the inner wall surface of the through hole 5 as shown in FIG. 4. The As described above, since the plating film 6 covers the entire surface of the substrate body 1 and the through hole 5, the outer shape is covered with the plating film 6 even after the plating process, but is substantially the same as the substrate body 1 and the through hole 5. Accordingly, the surface of the substrate body 1 and the inner wall surface of the through hole 5 may be referred to as the surface of the substrate body 1 and the inner wall surface of the through hole 5 even when the plating film 6 is interposed between the surface of the substrate body 1 and the inner wall surface of the through hole 5.

Next, an insertion process (step S4) is performed. In this step, the heat conductor 7 is inserted into the through hole 5. Therefore, as shown in FIG. 5, the heat conductor 7 is placed in the through hole 5. The heat conductor 7 is formed by machining a metal plate or bar into a substantially cylindrical shape. Specifically, it is formed by punching a metal plate into a substantially cylindrical shape or appropriately cutting a long, substantially cylindrical rod material to a predetermined length. As a material of the heat conductor 7, a metal material having heat conductivity, for example, copper is used. At this time, the outer peripheral surface of the heat conductor 7 and the inner wall surface of the through-hole 5 (the plating film 6 in the through-hole 5 in the example of FIG. 5) are separated from each other, and a gap portion 8 is formed.

Next, a fixed plating process (step S5) is performed. In this step, plating is performed in a state where the heat conductor 7 is held in the through hole 5, and the fixed plating portion 9 made of plating is formed in the gap portion 8. This plating process is performed by a normal plating process, that is, by immersing the substrate body 1 in a plating solution in which a metal to be deposited is dissolved as ions. At this time, as shown in FIG. 6, substantially plate-shaped holders 10 are arranged on both surface sides of the substrate body 1 (both end surfaces of the through hole 5). The holder is formed in a mesh shape or a porous shape, and has a shape that does not hinder the flow of the plating solution. For example, a porous body such as a resin porous plate can be used.

The holder 10 is formed by stacking a porous sheet 19 and a porous plate 20, and the porous sheet 19 is arranged on the substrate body 1 side. The porous sheet 19 further includes a through hole 21 having a diameter smaller than the diameter of the heat conductor 7. By providing this through hole 21, plating can be favorably deposited. By arranging such a holding tool 10, it is possible to prevent the heat conductor 7 from coming out of the through hole 5 during the plating process due to liquid flow or gravity, or being displaced from the through hole 5. Is done. Note that the holder 10 may be used only on one side of the substrate body 1. Further, if the substrate body 1 and the holder 10 are directly overlapped, the holder 10 cannot be removed from the substrate body 1 due to plating deposition, so that a gap is provided between the substrate body 1 and the holder 10. It is preferable to perform a mask process.

When a fixed plating process is performed using such a holder 10, as shown in FIG. 7, a fixed plating portion is provided between the holder 10 and the substrate body 1 and between the heat conductor 7 and the through hole 5. 9 is formed. Here, the fixed plating part 9 formed between the heat conductor 7 and the through hole 5 is formed by the plating solution entering the gap part 8. Considering the formation of narrow pitch thin wires in the circuit formation by the subtractive method in the subsequent process, the distance of the gap 8 is preferably 50 μm to 70 μm. However, this distance is not a sufficient distance for the plating solution to circulate. Therefore, the plating deposition amount is reduced, and it is difficult to reliably fix the heat conductor 7 to the through hole 5.

Therefore, in the above-described through hole forming step, as shown in FIG. 8, a plurality of substantially semi-cylindrical protrusions 22 that bulge outward from the inner wall surface of the through hole 5 along the through direction of the through hole 5 are formed. To do. That is, in the through hole forming step, first, a plurality of small holes 25 each having a substantially cylindrical inner space serving as the protruding portion 22 are formed using a drill or the like. The plurality of small holes 25 are provided so as to be spaced apart from each other, and are formed such that the centers thereof are arranged on the same circumference in plan view (direction seen from the front in FIG. 7). Next, based on the circumference where the center of the small hole 25 is arranged, the large hole 26 whose inner space is a substantially cylindrical through hole is formed. Thereby, the through-hole 5 in which a plurality of protruding portions 22 whose inner wall surfaces bulge outward can be obtained. The through-hole 5 has a shape in which a plurality of approximately year-shaped protrusions bulge out with a space on the outer side in the circumferential direction of the large hole 26 in plan view. When the heat conductor 7 is inserted into such a through hole 5, the gap 8 is formed with a non-constant interval between the outer peripheral surface of the heat conductor 7 and the inner wall surface of the through hole 5 opposed thereto. That is, the distance between the outer inner wall surface formed by the protrusion 22 and the heat conductor 7 is the maximum portion 23 that is the maximum distance, and the distance between the other inner wall surface and the heat conductor 7 is the minimum distance. It becomes a certain minimum portion 24.

Thus, since the gap portion 8 has the minimum portion 24 that is the minimum interval and the maximum portion 23 that is the maximum interval, the plating metal for forming the fixed plating portion 9 is passed through the maximum portion 23 (projecting portion 22). And can be fully filled. That is, since the plating solution flows into the protruding portion 22 having the maximum portion 23 during the plating process, the plated metal can be reliably deposited around the heat conductor 7. Furthermore, by providing the maximum portion 23, the contact area between the heat conductor 7 and the through-hole 5 through the fixed plating portion 9 can be increased, and a stronger fixation becomes possible. The conductor 7 can be fixed in the through hole 5. Considering the efficiency of the plating solution circulation in the protrusion 22, the diameter of the small hole 25 is preferably about 25% with respect to the thickness of the substrate body 1. If the interval between the adjacent protrusions 22 is about 100 μm to 1 mm, the plating is stably filled.

In addition, the protrusion part 22 for providing the maximum part 23 and the minimum part 24 is an example to the last, and the space | interval between the outer peripheral surface of the heat conductor 7 and the inner wall surface of the through-hole 5 which opposes this is formed as non-constant. In this case, the maximum portion 23 and the minimum portion 24 are naturally formed. Therefore, as long as a space for sufficiently circulating the plating solution can be provided, the shape of the through-hole 5 in a plan view may be formed in any way, and conversely, the heat conductor 7 may be recessed inside. The shape may be changed.

In the present embodiment, the internal space of the through hole 5 and the heat conductor 7 are formed in a substantially cylindrical shape, and the maximum portion 23 further bulges outward from the inner wall surface of the through hole 5 along the through direction of the through hole 5. It was formed by a cylindrical protrusion 22. If it is set as such a shape, since the through-hole 5 can be easily formed along the above procedures, it is preferable from a viewpoint of workability.

When the holder 10 and the substrate body 1 are taken out of the plating solution after the plating process is completed, the fixed plating portion 9 is formed between the surface of the substrate body 1 and the heat conductor 7 and the through hole 5 as shown in FIG. A heat dissipation substrate 27 is formed. Both surfaces of the heat dissipation substrate 27 are flush with each other by physical polishing such as buffing.

Next, a circuit formation process (step S6) is performed. In this step, the plating film 6 and the fixed plating portion 9 formed on both surfaces of the heat dissipation substrate 27 are removed by an etching process or the like to form a conductor pattern 11 as shown in FIG.

Then, a solder resist coating process (step S7) is performed. In this step, as shown in FIG. 11, solder resist 12 made of an insulator is applied to both surfaces of the heat dissipation substrate 27.

Then, a land formation process (step S8) is performed. In this step, as shown in FIG. 12, a part of the solder resist 12 is removed, and an area where the electrical or electronic component 13 is to be mounted is exposed as a land 14. The lands 14 are formed so as to correspond to both surfaces of the heat dissipation board 27, respectively.

Then, a component mounting process (step S9) is performed. In this step, as shown in FIG. 13, the component 13 is mounted on the land 14 via the solder 16. Thereby, the component 13 and the thermal conductor 7 are thermally connected via the solder 16. That is, a heat dissipation path for heat generated from the component 13 is secured. Note that the component 13 and the heat conductor 7 may be thermally connected not by using the solder 16 but by using another heat transfer resin, heat transfer sheet, or the like. A sheet-like heat conductive sheet 17 made of a conductive material is attached to the land 14 on the surface opposite to the surface on which the component 13 is mounted. A heat sink 18 is attached in contact with the heat conductive sheet 17. That is, the heat radiation path from the component 13 starts from the component 13, the solder 16, the fixed plating portion 9 on the component 13 side, the heat conductor 7, the fixed plating portion 9 on the opposite side of the component 13, the heat conductive sheet 17, and the heat sink 18. Heat is transferred in this order.

1: substrate body, 2: conductive layer, 3: insulating layer, 4a: single-sided plate, 4b: double-sided plate, 5: through-hole, 6: plating film, 7: thermal conductor, 8: gap, 9: fixed plating Part: 10: holder, 11: conductor pattern, 12: solder resist, 13: parts, 14: land, 15: heat dissipation substrate, 16: solder, 17: heat conduction sheet, 18: heat sink, 19: perforated sheet, 20 : Perforated plate, 21: Through hole, 22: Projection, 23: Maximum part, 24: Minimum part, 25: Small hole, 26: Large hole, 27: Heat dissipation board

Claims

An insulating layer made of an insulating resin material;
A conductive layer made of a conductive material;
A substrate body comprising the insulating layer and the conductive layer;
A through hole penetrating the substrate body;
A heat conductor made of a heat transfer material accommodated in the through hole;
A gap existing as an interval between the through hole and the thermal conductor;
A fixed plating portion formed by plating in the gap portion to fix the thermal conductor in the through hole;
The gap portion is formed such that the interval between the outer peripheral surface of the heat conductor and the inner wall surface of the through hole facing the heat conductor is non-constant, and includes a minimum portion which is a minimum interval and a maximum portion which is a maximum interval. A heat dissipating board characterized by comprising:
The internal space of the through hole and the heat conductor are substantially cylindrical.
2. The heat dissipation according to claim 1, wherein the maximum portion is formed by a substantially semi-cylindrical protruding portion that bulges outward from an inner wall surface of the through hole along a penetration direction of the through hole. substrate.
A substrate body forming step of forming a substrate body in which a conductive layer made of a conductive material is formed on an insulating layer made of an insulating resin material;
A through hole forming step in which the internal space penetrating the substrate body forms a substantially cylindrical through hole; and
An insertion step of inserting and arranging a substantially cylindrical heat conductor made of metal in the through hole; and
A fixed plating step of performing a plating process in a state where the thermal conductor is held in the through hole, and forming a fixed plating portion made of plating in a gap portion existing as a gap between the through hole and the thermal conductor; With
In the through-hole forming step, a plurality of substantially semi-cylindrical protrusions bulging outward from the inner wall surface of the through-hole along the through-direction of the through-hole are formed. .
4. The method of manufacturing a heat dissipation substrate according to claim 3, wherein a holder made of a porous body through which a plating solution can pass is disposed at both ends of the through hole in the fixed plating step.